If the rss feed goes to a pages that has a nice link to get a printer friendly version that is clean. Then this method can work really well for you in most cases. You will have to know a little bit about regular expressions or of course you can do like I do and cheat and use firebug to get the link say for instance /services/printVersion.asp then let http://www.txt2re.com/index.php3
convert it to python reg expression.
then you could use code like this...
put this at the top to allow for the use of the tempfile usage
from calibre.ptempfile import PersistentTemporaryFile
then in your recipe simply add this code block and change only the urlreg=